docs: def worker(job):
      """Primary |worker| coroutine. This is a |pull| object that pulls jobs from
      a source and yield evaluated results.
  
      Input should be of type |JobMessage|, output of type |ResultMessage|.
  
      .. |worker| replace:: :py:func::`worker`"""
      if job is EndOfQueue:
          return
  
      if not isinstance(job, JobMessage):
          print("Warning: Job should be communicated using `JobMessage`.",
                file=sys.stderr)
  
      key, node = job
      return run_job(key, node)